The present invention relates to an electrically powered retractable door mirror for a vehicle and provides a secure and smooth support structure for a horizontal worm gear included in a reducer.
An electrically powered retractable door mirror for a vehicle is designed to be able to position a mirror body supporting a mirror at a returned position (a position in use, an upstanding position) or a stored position alternatively, driven by a motor and operated by remote control.
FIG. 2 is an exploded oblique perspective view of a general structure of an electrically powered retractable door mirror (used on the right-hand side of the vehicle). On the door of the vehicle, a base component (not shown) for installing a door mirror is installed. On a horizontal portion hanging over outside of the vehicle, a shaft 10 is installed and fixed vertically in a standing position. On a lower horizontal portion 10a of the shaft 10, a washer 12 is installed.
On a frame body 14, a mirror body (not shown) is installed. The frame body 14, on the under surface of which a plate stopper 16 is installed, is installed in a way that the frame body can rotate on the shaft 10 freely. When the motor-driven frame body 14 (mirror body) is opening up from the stored position, at the given returned position step portions 16a, 16a of the lower end of the plate stopper 16 contact and engage with trapeziform stoppers 10b, 10b formed at the upper surface of the lower horizontal portion 10a of the shaft 10, and the plate stopper 16 is stopped. By this, the frame body 14 stops in the returned position.
When the frame body 14 is closing down from the returned position driven by a motor, or when the frame body 14 is closing down from its returned position affected by external force applied to the mirror body from the vehicle""s front to rear direction, at the given stored position a protruded portion 16b on the inner circumference of the plate stopper 16 contacts and is engaged with one side 10ca of a stopper 10c of the lower portion of the shaft 10. Because of this, the frame body 14 stops at the stored position.
Additionally, if external force is applied to the mirror body from the vehicle""s rear to front direction when the frame body 14 is in its returned position, the step portion 16a of the plate stopper 16 gets over trapeziform stoppers 10b, 10b on the lower horizontal portion 10a of the shaft 10. As a result, the frame body 14 collapses toward the vehicle""s front side. At this moment, at the given position, the protruded portion 16b on the inner circumference of the plate stopper 16 contacts and is engaged with the other side 10cb of the stopper 10c of the shaft 10. By this, the frame body 14 stops in that position.
Inside a box 28 of the frame body 14, (a gear 18), a plate clutch 20, a coil spring 22 and a washer 24 are housed by letting them through the shaft 10 one by one. In relation to the shaft 10, the gear 18 is supported so as to be rotatable and move axially, and the plate clutch 20 is supported to be able to move axially but not to be rotatable. A plate 26 (fastener) inserted in a groove 10d formed near the upper end of the shaft 10 presses down the washer 24 to compress the coil spring 22, causing the above-mentioned parts 10, 12, (16), 14, 18, 20, 22, 24 and 26 to be integrated.
Inside the box 28, a shaft 30 is installed in a standing position. On the shaft 30, a gear 32, in which upper and lower gears are integrated, and a worm gear wheel 34 are supported so as to be able to rotate freely. Further inside the box 28, a two-step worm gear comprising a horizontal worm gear 36, a worm gear wheel 38 and a vertical worm gear 40 are housed. The horizontal worm gear 36 has a shaft arranged horizontally and supported on both ends by plate ends 42, 44 (metal plates) that are held on wall surfaces facing each other inside the box 28 thus blocking axial movement of the horizontal shaft. The horizontal worm gear 36 engages with the worm gear wheel 34.
On the horizontal worm gear 36, the worm gear wheel 38 is coaxially fixed. The vertical worm gear 40 has a shaft arranged vertically with a ball steel 46 inlet in the lower end of the vertical worm gear 40, and is supported axially by the ball steel 46 on a bush 48 embedded in the bottom inside the box 28. The vertical worm gear 40 engages with the worm gear wheel 38.
The opening end of the upper portion of the box 28 is covered by an outer plate 50 (lid) and the outer plate is fastened with screws 60. The frame body 14 and the outer plate 50 comprise a frame 15. On the upper surface of the outer plate 50, a motor 52 is installed by being fastened with screws 62. A rotating shaft 54 of the motor 52 is let into the box 28 through a hole 56 in the outer plate 50.
Inside the box 28, a washer 58 is let through the rotating shaft 54 of the motor 52; the tip of the rotating shaft 54 is let through a hole at the upper end of the vertical worm gear 40; and the rotating shaft 54 and the vertical worm gear 40 are interlinked. On the side of the casing of the motor 52, a plate circuit sub-assembly 64 is installed on which the control circuit of the motor 52 is loaded. The outer plate 50 is covered by a seal cap 66.
According to the above-mentioned configuration, when the motor 52 is driven, its rotation is transmitted to the vertical worm gear 40, the worm gear wheel 38, the horizontal worm gear 36, the worm gear wheel 34, the gear 32, and to the gear 18. At normal operation (no external force is applied), because the gear 18 engages with the non-rotatable plate clutch 20 at their convexo-concave portions formed on end surfaces facing each other, an axial rotation of the shaft 10 is blocked.
Consequently, the gear 32 goes around the gear 18. By this, the frame body 14 rotates on the shaft 10. When the motor 52 is started from the stored position, the frame body 14 reaches the returned position and step portions 16a, 16a of the plate stopper 16 are engaged with stoppers 10b, 10b of the shaft 10, or when the motor 52 is started from the returned position, the frame body 14 reaches the stored position and the protruded portion 16b of the plate stopper 16 is engaged with one side 10ca of the stopper 10c of the shaft 10, and the motor 52 is locked.
At this time, the control circuit on the plate circuit sub-assembly 64 detects that the motor is locked by detecting a change in driving current of the motor 52 (which is overcurrent) and stops the motor from driving (stop control by the gear lock method).
Additionally, if external force is applied to the mirror body from the vehicle""s front to rear direction when the mirror body is in the returned position, resisting to the momentum acquired by the coil spring 22, engagement of the gear 18 and the plate clutch 20 comes off. This enables the gear 18 to axially rotate on the shaft 10. By the external force, the mirror body is closing down in the direction of the stored position, letting off the external force.
Additionally, if external force is applied to the mirror body from the vehicle""s rear to front direction when the mirror body is in the returned position, engagement of the step portion 16a, 16a of the plate stopper 16 and the trapeziform stopper 10b, 10b comes off, and at the same time, engagement of the gear 18 and the plate clutch 20 comes off. This enables the gear 18 to axially rotate on the shaft 10. The mirror body collapses toward the vehicle""s front side by the external force, letting off the external force.
A conventional support structure of the horizontal worm gear 36 is shown in FIG. 3. At the bottom inside the box 28, protruded portions 68, 70 are formed. At the upper end of the protruded portions 68, 70, concave portions 68a, 70a are formed. On the under surface of the outer plate 50, convex portions 72, 74 are formed in positions facing the concave portions 68a, 70a. 
By placing shank portions 36a, 36b located on both sides of the horizontal worm gear 36 into the concave portions 68a, 70a, and installing the outer plate 50 by laying it over the opening end of the upper portion of the box 28 and fastening it with screws 60 (FIG. 2), as shown in FIG. 4, the convex portions 72, 74 are inserted into the concave portions 68a, 70a, and the shank portions 36a, 36b of the horizontal worm gear 36 are fixed between the lower end surfaces 72a, 74a of convex portions 72, 74 and the concave portions 68a, 70a. 
According to the support structure of the horizontal worm gear 36 shown in FIG. 3 and FIG. 4, because the horizontal worm gear 36 is supported by the concave portions 68a, 70a on the side of the frame body 14 and the lower end surfaces 72a, 74a of the convex portion 72, 74 on the under side of the outer plate 50, the horizontal worm gear 36 rattles or is compressed due to building differences between the frame body 14 and the outer plate 50 (a motor installation component), occasionally preventing the horizontal worm gear 36 from rotating securely and smoothly.
The present invention intends to solve problems in the above-mentioned conventional technologies, and to provide an electrically powered retractable door mirror in which secure and smooth rotation of the horizontal worm gear can be obtained by making the horizontal worm gear less affected by building differences between the frame body and the motor installation component.
The present invention describes an electrically powered retractable door mirror which comprises a frame supported on a shaft formed on the vehicle side being able to rotate freely and a mirror body installed on the frame, which has a structure wherein a motor and a reducer are installed on the frame, the driving force of the motor is transmitted to the shaft through the reducer, the frame is axially rotated on the shaft and the mirror body is moved to its returned position or stored position, and in which the frame possesses a frame body and a motor installation component, the motor is installed on the motor installation component and a horizontal worm gear is included in the reducer.
The electrically powered retractable door mirror comprises: on one of the frame body or the motor installation component a horizontal worm gear bearing which supports the shank portion of the horizontal worm gear by encircling the periphery of the shank portion; in the horizontal worm gear bearing, a notch linking up to a space inside the bearing is formed by cutting off a part of the horizontal worm gear bearing in its peripheral direction; the width of the notch is formed narrower than the diameter of the shank portion of the horizontal worm gear. By inserting the shank portion of the horizontal worm gear in the space inside the horizontal worm gear bearing through the notch by deflecting the horizontal worm gear bearing in a direction that opens up the notch, the horizontal worm gear is supported on the horizontal worm gear bearing. And on the other one of the frame body or the motor installation component, flexure control portions are provided, which control flexure of the horizontal worm gear bearing in the direction that the notch opens up by bringing the motor installation component installed on the frame body into contact with the horizontal worm gear bearing.
According to the present invention, because the horizontal worm gear is supported on the horizontal worm gear bearing by inserting the shank portion of the horizontal worm gear into the space inside the horizontal worm gear bearing through the notch by deflecting the horizontal worm gear bearing in the direction that the notch opens up, the horizontal worm gear is able to be supported on one of the frame body or the motor installation component, and the supporting position of the horizontal worm gear is less affected by building differences between the frame body and the motor installation component.
Furthermore, in the configuration in which the frame body and the motor installation component are built, the flexure control portions provided on the other of the frame body or the motor installation component contact the horizontal worm gear bearing, controlling flexure of the horizontal worm gear bearing (i.e., the notch opens up) by gear reaction force while the horizontal worm gear is in operation. By this, the horizontal worm gear is able to rotate securely and smoothly.
In the present invention, for example, the horizontal worm gear bearing and the flexure control portion are arranged opposite one another with the motor installation component and the frame body facing each other. By arranging the motor installation component opposite to the installation position of the frame body, a structure, in which the flexure control portion controls the flexure in a direction that the notch of the horizontal worm gear bearing opens up by contacting the horizontal worm gear bearing, is provided.
The notch is formed on the side of the horizontal worm gear bearing, which faces the other of the frame body or the motor installation component. Holding the horizontal worm gear between both sides of the horizontal worm gear bearing, the flexure control portion is able to control the flexure in the direction that the notch opens up.
Additionally, for the horizontal worm gear bearing, a material with sliding property and abrasion resistance higher than a material used for the flexure control portion can be used. For the flexure control portion, a material with rigidity higher than a material used for the horizontal worm gear bearing can be used. Conventionally, to sustain gear reaction force, rigid resins such as those containing glass fiber had to be used for horizontal worm gear bearings. Due to this, it was difficult for the flexure control portion to have both sliding property and abrasion resistance. By using different materials for the horizontal worm gear bearing and the flexure control portion, necessary rigidity, sliding property and abrasion resistance can be successfully combined.
Additionally, the horizontal worm gear bearing can be formed using a synthetic resin in a way that it is integrated with one of the frame body or the motor installation component, and the flexure control portion can be formed using a synthetic resin in a way that it is integrated with the other of the frame body or the motor installation component.
Additionally, the shape of a cross section meeting at right angles with the shaft of the space inside the horizontal worm gear bearing can be formed in a circle and the notch can be formed within the range below 180 degrees of the circumference of the circle.
Additionally, the motor installation component comprises a lid for the box housing the shaft and the reducer. The motor is installed outside of the lid, and it can be structured such that the rotating shaft of the motor passes through the lid and is inserted inside the box.